The invention concerns a centrifuge drum for concentrating suspended solids, which are conveyed through channels out of an outer solids space in the drum and into a radially inner peeling chamber, whence they are diverted by a peeler and by an associated concentrate line, whereby a separated clear phase is continuously extracted from the interior of the drum by another peeler and by an associated clear-phase line.
A similar drum is known from German 2 701 624 C2. The first peeler in the known drum constantly diverts concentrated solids out of the drum. The stationary peeler immerses itself for this purpose in the concentrated solids, which are rotating within the peeling compartment at the same speed as the drum, converting the energy of rotation into feed pressure. Friction generates heat where the concentrated solids come into contact with the peeler, and the heat transfers to the concentrate. When the solids are insensitive to heat or when there is a lot of them, the heating is either safe or negligibly slight. In biochemistry, however, the concentrates are often of living cells and highly sensitive to heat. Their volume is also often very low. In either case the heat of friction can be very detrimental or even intolerable. These conditions occur both when a small volume of solids is continuously extracted and when a large volume is extracted periodically and rapidly.
In the latter situation the concentrate line must be turned off after each extraction. The peeler, which is still immersed in the liquid in the peeling compartment, can become hot between the periodic diversions, in which case any contact between it and sensitive solids during the next diversion will be highly detrimental.